The present invention relates generally to dental implants and more particularly to a basal osseo integrated jaw implant for receiving and securing a prosthesis such as a crown, a web or a bridge.
Basal osseo integrated, lateral jaw implants, may be inserted in an implant bed which is surgically placed in the upper or lower jaws. After sufficient healing, lateral jaw implants serve as a means for securing a crown, artificial teeth or prosthetic tooth constructions. These jaw implants are already generally known in many different embodiment forms. These jaw implants are composed substantially of a ring or disk-shaped foot part which is connected through a web to a shaft that is orthogonal to the foot part. The shaft has at its free end an abutment without a thread, for securing a dental overstructure or an external and internal thread for receiving the abutment.
The known solutions can be subdivided into jaw implants with a single-part design or those with a multi-part design, and are disclosed for example in such patent documents as FR 75 07 078, EP 0 214 962, and DE 298 12 642.
Despite the good results which are obtained with the known jaw implants, it has been shown that with the formation of the implant bed and the insertion of the implant into a surgically produced opening, it is very difficult to perfectly adapt the implant into the anatomy of the upper and lower jaws, without having to subsequently re-position the implant. Also, it is often necessary to subsequently adjust the implant by bending the implant web. Naturally, this can be performed only to a limited extent and with the danger of loosening the jaw implant in the upper or lower jaws. The known basal osseo integrated jaw implants have a shape which is often not suitable for the treatment course.
The patent documents FR 2 302 715, EP 0 388 576 and EP 0 214 962 further disclose the construction of jaw implants in which the upper surface of the foot part of the implant and the transition region of the shaft to the web, the so-called shaft neck, are increased by a jet process, an etching process or combined methods, or the transition region is provided with a profiling or a special structure for supporting the secure seating of the implant shaft in the jaw bone. However, in practice it has been shown that due to the structure and the surface increase in this transition region, irritations and inflammations of the connecting tissue may result during the healing process. In addition, the surface increases can lead to an accumulation of bacteria, which can detrimentally affect the healing process and the permanent, secure seating of the jaw implant in the upper or lower jaws.
Accordingly, it is an object of the present invention to provide a jaw implant, which avoids the disadvantages of the prior art.
More particularly, it is an object of present invention to provide a jaw implant which, due to a suitable design of the foot part, guarantees wide possibilities for the adaptation of the implant to the varying anatomies in the formation of upper and lower jaws, allows for simple insertion, and provides for complication-free growth of the implant into the jaw bone and secure and permanent fit.
In accordance with the present invention is provided a jaw implant for mounting a dental prosthesis such as artificial teeth, including a force-transmitting foot part for insertion into a jaw; a shaft which is generally orthogonal to the foot part and having a distal end and a base operatively connected to the foot part; and the foot part and a portion of the shaft adjacent thereto having a surface increase for implanting; a portion of the shaft adjacent the distal end having a smooth, non-irritating surface; and the surface increase portion of the shaft being about one-half the total length of the shaft
The basal osseo integrated jaw implant in accordance with the present invention preferably has a combined, disk-shaped and ring-shaped foot part comprised of different geometric base forms, on which the shaft for receiving and securing a tooth replacement is connected through a web. The web is arranged preferably eccentrically to the center of gravity of the foot part and connects together the portions of the foot part of the different geometrical forms. The foot part, the web and the transition region of the shaft to the web is provided with a surface increase produced in a known manner with a jet, etching or combined processes, while the shaft in its head region has a smooth, non structured surface below the thread or the abutment.
Substantial conformity of the foot part of the jaw implant to the opening produced by the milling in the upper or lower jaw is guaranteed due to the fact that the load-supporting foot part is formed of circular/elliptical and rectangular/square geometrical form portions and the web is arranged eccentrically to the foot part center of gravity and receives the shaft of the implant. Simultaneously, the configuration of the foot part thus formed prevents the inserted implant from turning in the surgically produced implant bed.
The ring-shaped edge, which is produced by recesses provided in the foot part on both sides of the web, together with the inventive configuration secures an exact placement of the foot part in the compacta of the upper and/or lower jaws and thereby provides conditions for a long term, fixed seating of the jaw implant.
In accordance with another embodiment of the present invention, the force-transmitting foot part is composed of two disk rings which merge into one another and are formed by circular or elliptic form bodies. The shaft, which is provided on the end side with a thread for securing an abutment, is arranged eccentrically to the foot part center of gravity through a web in the center of a disk ring. A web which is positioned at one side to the inside wall of the disk ring can be used as well, instead of a continuous web. As already mentioned, the foot part, the web and the transition region of the shaft to the web are provided with a known surface increase, while the shaft in its head region has a smooth, non structured surface.
With this type of implant, the occurring forces can be further transmitted from the shaft, for the reception and securing of the dental prosthetic overstructure in the upper or lower jaws. With the surgical introduction of the implant, the shaft can be seated on the prosthetically desired place, and a range of bone that is more remote from the shaft can be used for force transmission. It is especially advantageous to use this implant design in the region of the first and second upper molars, since generally there are still sufficient tuber bones available at a distance from this jaw region, in spite of the fact that there are no teeth required here. However, also in the lower jaw side tooth region the basal osseo integrated jaw implants with asymmetrical shaft arrangement are advantageous. The chewing force transmitting implant surfaces can thus be distributed over the jaw, while the shafts of the implants can be integrated in a favorable medial position against the centrifugal resorption of the lower jaw. When compared with the implants with flat longitudinal sides or implant sides, the implant forms with the foot part formed of two disk rings which merge into one another, has the advantage of a simpler introduction. For producing the implant bed, a round slot with cortical anchoring can be milled by merely using the same size milling tool. The milling extends in an advantageous manner from a single point and then, depending on the desired disk size, advances in the different directions with respect to the center points of the disk rings, which can even be angled relative to one another in a horizontal direction. In the implant bed produced by the corticalic penetration, the implant is first inserted with the shaft-free disk ring and then turned into the correct position.
Due to the eccentric arrangement of the web and shaft relative to the foot part center of gravity and the proposed configuration of the foot part, the conditions are provided for an easy and substantial adaptation of the implant to the different natural anatomy of the upper and lower jaws in the process of the surgical operation and, depending on the formation of the jaw bone crest, in most applications work can only be carried out in one milling direction. Counter milling for forming the implant bed as was often necessary with the use of implants having a central arrangement of the shaft and the foot part, but an asymmetrical base form (FR 7507078), can be dispensed with. The formation of the basal osseo integrated jaw implant in accordance with the present invention leads simultaneously to an improved shortening of the milling time for the implant bed and thereby of the length of the operations.
Subsequent adaptations and corrections after the ingrowth of the implant into the upper and lower jaws, for example by bending of the shaft, which naturally result in a danger of loosening of the implant in the jaw bone, can be avoided.
While the surface enlargement of the foot part, the web and in some cases the transition region and recesses provided in the foot part enhances a fast ingrowth of the implant and its secured seating in the upper and lower jaws, the shaft, which is free from the surface increase and structuring, prevents the formation of plaque in the thread-adjacent head region, while a microgap can be formed which is rinsed by natural salivation and promotes the formation of infection-free connecting tissue. Infections and inflammations of the connecting tissue are prevented in this region by the microgap and thereby the strong and reliable seating of the implant in the upper or lower jaws is also enhanced. It has been shown that with flexible implant systems, for example with constructions in the lower jaw or during work in upper jaws, infections, which later could lead to bone decay, occurred occasionally in only a few implants on the structured shaft.
Due to the microgap which is formed in the transition region, the shaft and the web of the jaw implant, which is firmly fixed in the compacta of the jaw bone, further have the ability under stress to act resiliently in the spongiosa of the jaw bone. Displacements occur in the regions of the jaw bone, which adjoin the web and the shaft. The likelihood of a long term fixed seating of the jaw implant is thereby also enhanced, while the force transmission is performed always in the compacta.
Advantageously, the height of the surface increases to the free smooth part of the shaft, amounts to at least half of the height of the shaft to the thread for securing an abutment or the like. The ratio between the height of the foot body and the height of the shaft is in the range of 1:6-1:30. Thus, it is possible, to provide a good osseo integration of the basal shaft portion far from the region of bacterial contamination.
In another preferred embodiment, the force-transmitting foot part of a one-piece jaw implant has a ring body with a web articulated laterally to the inside wall of the ring body and merging into a shaft which is orthogonal to the foot part and has a bendable neck. Connected to the bendable neck is an abutment integrated as one piece in the shaft for receiving the prosthetic overstructure, and the foot part can have a round or elliptical configuration. This jaw implant variant can be produced in a cost effective manner and has the advantage that after it is implanted in the mouth of the patient, the components of the implant need no further assembly nor to be screwed together.
When compared to the implants known in the art, the proposed jaw implant has substantial advantages in the sense of the required operational features for introduction in the upper and/lower jaw bones and with respect to the necessary adaptation work required during insertion of the overstructure.
Because the web is articulated with one side to the inside wall of the foot part and merges orthogonally into the shaft of the implant, it is unlikely that the connecting tissue will grow from the insertion side over the web of the foot part and into the region of the shaft. The progressive growth of the connecting tissue in the direction toward the shaft takes place namely over the webs. Surprisingly however it has been found that a reduction of the webs also leads to a decrease in the probability of loss for the implant, without increasing the frequency of breakage.
With a suitable choice of materials for the implant and a corresponding structural design of the neck part of the shaft, there is the possibility of bending the abutment in the mouth of the patient in the required direction and thereby to create the conditions for a parallel insertion of multi-bracing bridges.
Advantageously the abutment is measured in such a way that a cementing of the crown or the overstructure can be carried out, and with the embodiment of the implant as a simple cementing post it has an internal thread on the head side. Thereby it is possible to secure also screwable bridges on the implant. It is known that there is a problem that the bridges which are mounted exclusively by cementing are difficult to remove when this is required. However, the inventive solution makes it possible to secure a bridge simultaneously by cementing and screwing. Even if the screws become loose, the bridge is still held in its mounting to a limited extent and vice versa.
In accordance with a further embodiment of the present invention, the force-transmitting foot part is formed by several disk-shaped ring bodies which are spaced from one another, and which are joined via inwardly located webs and connected with one another by an additional shaft oriented orthogonally to the foot part. With this embodiment, an increase in the force-transmitting surfaces is provided in an advantageous manner. As is generally known, the forces are transmitted only in the region of the compact bone, i.e. in the region of the ring body of the foot part, which for this purpose is located completely inside the compactor of the bone.
The ring bodies which are located over one another and are spaced apart from one another can also have varying external diameters. At least one of the ring bodies, preferably the lower ring body, has a continuous web, which is positioned at an angle alpha of 30xc2x0-90xc2x0, preferably 90xc2x0, relative to another web affixed at one side to the inside wall of the other ring body. The foot parts thus formed allow for a substantial adaptation of the implant to the anatomical features of the upper and/or lower jaw and permit the full use of the bone width of the upper and/or lower jaw. The continuous web of the lower ring body is thus located completely in the spongiosa, soft bone region, while the upper web located at right angles to the continuous lower web is completely received by the compacta of the bone, which is not damaged by the milling.
The lower ring body can have a body form which deviates from the upper ring body and is cornered or combined, and has a smaller external diameter than that of the upper ring body. The implants with the foot parts thus designed are recommended in particular in the region of the arteria palatina where the crestal portion of the jaw crest is wider than the basal portion. A rupturing of the artery during the surgical operation for producing the opening for receiving the implant can thereby be avoided.
With a distance between the ring bodies of the foot part exceeding three millimeters, not only the placement of the implant is made easier and its hold in the upper and/lower jaw is improved, but also an improved blood supply of the inter discal region is provided, since the lateral flow from the direction of the mucus membrane is increased. Moreover, the lateral stability of the implant increases. Furthermore, the basal ring body is better protected in the event of bacteria settling on the crestal ring body.
Total implant losses are eliminated. Moreover, the removal of the implant or a disk of the implant is made easier. The insertion of the implant can also be performed more reliably. In particular, for brittle, cortical bones there is less danger of tearing the osteotomised interdiscal region when the ring bodies are positioned further from one another.
In accordance with another embodiment of the present invention, the configuration of the force-transmitting foot part deviates from a square base shape, with at least one side of the base form having a ring-shaped semicircle, while the corners of the opposite side are rounded by radii. The web connecting the shaft with the foot part inaccordance with a particular embodiment is formed of one side and is attached to the inside wall of the semicircular shaped foot part portion. In a further embodiment of this implant type, the web is constructed of two sides and arranged on a vertical or horizontal implant axis. However, the implant shaft can also be connected to the force-transmitting foot part through a cross-shaped web or through several webs formed of one side and offset relative to one another at an angle of 120xc2x0.
Particularly with the combined body forms and the configuration which deviates from a square base form, the foot part corresponds almost identically to the form of the implant bed produced by milling and completely fills it.
Altogether the present invention achieves the preconditions for a substantial adaptation of the implant to the anatomy of the upper and lower jaws, for a relatively simple surgical procedure, for a fast and largely complication-free healing of the implant and for a permanent, reliable and secure seating of the implant in the upper or lower jaws.